Die for stamping tapered tubiform elements



Dec. 24, 1940. l K. T. NoRRls 2,225,710

DIEy FOR STMPING TAERED TUBIFORM ELEMENTS Filed Feb. 1'1, 193s JM ji-'f6.4'.

i @Mcm/V A Homey Patented Dec. 24, 1940 PATENT OFFICE DIE FOR, STAMPING TAPERED TUBIFORM ELEDIENTS Kenneth T. Norris, Los Angeles, Calif.

Application February 11, 1938, Serial No. 190,025

8 Claims.

collars, sleeves, bands, rings, cylinders and the like, from sheet metal stock and also resides in the provision of a new and improved compound die with which the method hereof and otherl advantageous operations may be carried out with a saving in time, material and costs, and an acthe iinished products.

curate uniformity in the finished products.

One of the objects of this invention is to provide a die of the character described, by means of which sheet metal stock is blanked, drawn,

pierced, and then drawn to nal shape in one continuous operation, to form tapered tubular members or what may be termed tapered hollow cylinders, characterized by dimensional and shape uniformity and surface smoothness and adapted y.for various uses, for example, the construction of collapsible tubular bodies in the manufacture `of drinking cups, pouring spouts and the like.

Another object of this invention is to provide a die structure such as described, wherein the ,taper given the work during the stamping operation sets up Work holding forces which effectively prevent slipping or other movement'of the work relative to certain elements of the die and thereby insure dimensional andrtaper uniformity in A further object is to provide a compound die of the character described wherein a die element thereof which moves with the work to effect the drawing thereof to iinal form, is provided with a .work engaging face formed or treated to effectively prevent movement of the work relative to said face during said final operation.

I have shown a preferred embodiment of my improvements in the accompanying drawing, subject to modification, within the scope of the appended claims, without departing from the spirit of my invention. i

Fig. 1 represents a vertical sectional view of a die constructed in accordance with this invention and showing the elements in normal position as before starting a stamping operation;` i

Fig. 2 represents a cross sectional view takenV on the plane of line 2-2 of Fig. 1;

Fig. 3 represents an enlarged fragmentary vertical sectional view taken through the die showing the position of parts thereof during the-first stage of operation as when drawing the stock, the die elements having traveled through approximately one-half of the full stroke thereof;

Fig. 4 represents an enlarged fragmentary vertical sectional view of the die, as when the piercing operation has been completed, following the operation shown in Fig. 3 and before the iinal drawing operation;

Fig. 5 represents an enlarged fragmentary sectional view showing the die elements and the work as when the stamping operation has been completed;

Fig. 6 represents a perspective view of the blank;

Fig. 7 represents a perspective view of the product as when the first drawing operation has been completed;

Fig. 8 represents a perspective view of the product as when the piercing operation has been completed;

Fig. Qrepresents a perspective View of the nished product which has been drawn to iinal shape from the form, as indicated in Fig. 8. n

lIn carrying out the method' of this invention to produce in one continuous stamping operation from sheet stock, a tapered tubiform member, the stock is first blanked, then drawn into the form of a tapered inverted cup, then pierced and iinally again drawn to produce a tapered cylinder free from flanges or irregular formations at the edges and fully open at its ends. Heretofore it has been the practice in making taperedr tubiform members to iirst blank and draw the stock in the form of a cup in one operation, and then as a separate operation, pierce the cup. Such methods required the use of separate dies and presses. With the method of'this invention but one die unit is used and the four operations are continuous andare respectively: blanking, drawing, piercing and drawing. The rst drawing operation produces a partially formed tapered member like an inverted cup, having a closure wall at its upper end and immediately that this is formed, the piercing operation takes place, so as 40 to remove all of -said closure except a small inwardly extending annular flange, and the iinal operation draws the work so as to draw or straighten out the flange and lengthen the tubi form element to its completed form, as shown in Fig. 9. Under this method the taper which hasl been formed in the work up to the time that the punching operation has been completed and the final drawing operation commences, is an important factor in that it sets up work holding forces preventing relative movement between the work and the movable die elements during said final drawing operation, it being noted that if the work is permitted to move relative to said die elements, an error as to the dimensional characteristics of the finished products will take place, and it will be impossible to obtain uniformity in the finished products. The method further contemplates the step of creating a pronounced work holding force eected thru the movable element of the die against the work during the nal drawing operation and the completion of the product,y

this force being substantially nil or ineffective during the other stages of operation of the die. The creation or application of this4 force as aforesaid, will insure the movement of the movable die element and the work as one and positively prevent relative movement between the work and said element during the final operation, although primarily the taper in the work, especially when pronounced, will prevent such relative movement and insure uniformity in the finished products.

I have provided a compound die with which the methods of this invention and other methods may be carried out in a particularly eilicaciousl manner. As here shown thisA compound'die primanly comprises a movable compound die element A and a stationary compound,A die element B. The movable die element A primarily includes a holder` I secured by ay clamp 2 to va press, not shown, a tubular punch and 'die member 3 xed in any suitable manner to said holder, and a piercing punch 4 fixed to said holder and extending .into the bore of the tubular punch and die member 3. Surrounding the piercing punch 4 and having a working i'lt in the bore of the member 3 is a knock-out sleeve 5 for ejecting the finished work from said member 3. 'I'his sleeve 5 is opergated to eject the work by means of a plunger 6 arranged in the holder I to depress pins 'I resting on an annular ange 8 of said sleeve. This flange is movable in a counterbore 9 of the tubular member 3. 'I'he plunger 6 is actuated by suitable elements of the press, ynot shown, which elements are a part of the usual press means for moving the die element A as a whole into and out of operative relation to the stationary`r dieelement B as is customary in the art. The tubular compound .punch and die element 3 has an outer edge serving as a blanking punch IU and an innerdie face II serving as a drawing die. This face or drawing die ,II isftapered 'andlpreferablylconstructed, formed, or treated to positivelyhold the blank from slipping or otherwise movingv relative thereto, as will be hereinafter more fully described. One way of preventing the blank or work from slipping is to form, as here shown,`a series of annular ribs and grooves as indicated by the numeral I2, whereby a serratedonroughened die face is provided for effectively gripping and holding the work.

-Thecompound and stationary die element B generally includes a die block I3 secured to the bed of the press, not shown,` by means of Va holder I4; a blanking die I5.xed in'said blockfanda tubular piercing and forming die I6 fixed to said holder and extending into said blanking Adie so as to define an annular space between opposedporrtions ofthe die* and punch.` A blankholding sleeve. II is reciprocally mounted in said annular space and has a working t with therpiercing and forming die I6 and the blanking die I5. This blank holding sleeve II is spring loaded and thereby yieldingly held in postionto cooperate withvthe tubular punch ,3 for holding the blank during thek initial stages of the stampinggoperaT/.19.111 AS` hereshownnsuitable.spring means I8..4

on the holder I4 operate thru a pin I9 to yieldingly support the sleeve I1.

In the operation of the compound die of this invention, as the movable element A thereof is moved to cooperate with the stationary element B, the punch 3 engages the sheet metal or other sheet stock lying on the blanking die I5 and thereby cuts out a circular imperforate blank C, as shown in Fig. 6.

As the blank holder I1 is normally disposed with its outer end spaced slightly inwardly of the plane of the outer face of the blanking die, the'blank is gripped between the lower end of the punch 3 and said holder immediately following the blanking operation. At substantially the same time that the blank holder and punch 3 grip the blank, thefini'tial drawing operation of the blank commences, inasmuch as the annular marginal portion D of the blank then engaged between said blank holder and said punch will be drawn downwardly, as indicated in Fig. 3, relative to the central'` body E of the blank, which latter isr then supported by and. extends over the outer end of the piercing and forming die I5. It should be noted that thel outer end of. the die I6 is slightly inwardly spaced'irom the outer face of the holder I'I, whereby to allow forv gripping of the blank in advance of the start of the first drawing operation. As this initial drawing operation takes place, the outer face of die I6.and die faceI I cooperate to form a tapered circular portion F (see Fig. 3) dened between the marginal portion D and the body E, and as the drawing operationl continues the circular portion F is lengthened and the marginal portion DV is reducedin width. The outer face of the piercing and forming die I6 is tapered as at 26, corresponding to the taper of the die I I, and the outer end edge of said die is rounded as at 2|, to accommodate the drawing of the blankasv aforesaid.

As the drawing operation progresses from the stage, as shown in Fig. 3,y the blank is drawn to the form of an inverted cup, as shown in Fig. 7. At substantially` the same time that the blank hasbeen drawn to the form of an. inverted cup, as shownin Fig. 3, and before the nal drawingr operation which produces the. finished. work shown in Fig. 9, the die elements A and-Bcooperate to produce a tubiform,m`ember, as shown in Fig.` 4, this being the thirdoperation effectedin the progressive thrust of the .punch anddie .ele-

ment A. Referring more specicallyto this third tion of the body E Yof the blank and. there come,

to rest so that substantially atthe timek the blank assumesthe finished Ycup form,.the Vpunch 4-,will engage said body and then cooperate with the piercing and forming ydie I6 to cut outsaid body except for an annular inwardlyextendingportion G, as shownin Fig. 8.` The slug thus cut will drop thruthe punchingdiel `and a contiguous slug tube 22 fixed to the holderv III.r

The die element .A continues its thrust of rthe punch anddie member 3 after the .piercing operation, this movement of said member .having been continuousfromthe startof the ystamping oper,- ation, and the nal .operation-of drawing the blank to the iinished'form is then effected.- With reference to` Fig..4,l whereinthe elem-ents of the die. .are Dshowmin Vthe.. position assumedy When a piercing operation has been completed, it is 4Seen that the flange portion G of the blank lies upon the rounded upper end 2| of the die I6 and the circular tapered part of the blank F is engaged between the tapered faces II and 20 0f the drawing die and said die I6. At this time the upper part of the inner face of the portion F engages the upper part only of the face 20 and the lower part of said inner face is spaced clear of the lower part ofthe said face 20, as shown `in Fig. 4, whereas the outer face of the portion Fis closely engaged with the'die face Il except at the upper portion thereof where clearance is provided as `shown in Fig. 4. These clearances are necessary to effectvthe continuous drawing of the blank during the continuous movement of the member 3 and preliminary to the final drawing operation. With the parts in the positions shown in Fig. 4, further travel of the member. 3 will cause the blank to be moved bodily with the member 3 along the tapered face 20 of the piercing and forming die IB and the flange portion G will be drawn downwardly between the faces Il and 2li` and become smoothed out as a part and continuation of the annular wall F. The rounded end 2| permits of the smooth drawing of the flange G, as aforesaid. The die elements A and B are then separated as is customary in the art, and the `knock-out sleeve is actuated by the press operfully open and free from flanges at its ends and Y subject to many uses as aforesaid.

It should be noted that the method and die apparatus of this invention provide for a` continuous movement of the die elements while the four stages of y,operation take place, said stages being the blanking, initial drawing, piercing and final drawing of the work to finished form.

In accordance with this invention, throughout the time the blank is being drawn into the form of the inverted cup, as shown in Fig. 7, the die member 3 is moved relative to the body of the blank as the latter is then held by the upper end of the piercing and forming die I6. At the completion of this drawing operation the portion D of the blank is drawn from between the ends of the die member 3 and holder Il up into the die, into substantially the position shown in Fig. 4 and is then in such engagement with the die face Il that when the piercing operation takes place, the die and blank will move bodily as one, relative to the piercing and forming die I6, whereby to draw the blank into the finished tubular form free from end flanges or irregularities and fully open at its ends. If the die face Il is ribbed, as at l2, or otherwise roughened, the blank will be more effectively held against movement relative to said die face.

It will be seen that with the method and means of the invention a die stamping operation may be eflicaciously carried out to produce tapered tubiform members of uniform dimensions and in iinished form at a lower cost as to equipment, time and labor, than has been possible heretofore. While the die equipment here shown is designed for producing tapered tubiform elements of cir cular form, it is to be understood that it is within the scope of this invention to produce tapered tubiform elements of oval rectilinear or other shapes as desired, under the method, and with the structural features and arrangements hereof.

I claim: l 1. A compound die for producing tapered tubiform elements from sheet stock in one continuous l operation, includingk cooperating die devices, one of which is movable relative to the other for drawing a blank of sheet material to produce a cup-shaped member fully open and free of iianges at one end and closed at its other end, means included in said. devices and operating'to remove the central portion of the closed end and leave a iiange and means embodied in said device whereby continuation of the relative movement of said die devices will straighten out said flange and produce a tubiform element fully open and free of flanges at its ends. v

2. A compound die for producing tapered tubiform elements from sheet stock in one continuous operation, including a stationary die device, a continuously movable die device cooperating with the stationary device during its movement, for

continuously drawing a blank of sheet material.

with the stationary device during its movement,`

for drawing a blank of sheet material into tapered form wherein one end of the form is free `of flanges and open and the other end is closed, means included in said devices and operating au-` tomatically for piercing Ythe closed end of the blank and removing a .portion thereof so thata flange remains, and means embodied in said devices whereby a continued movement of said movable die device will draw said flange into position to form a tapered tubiform end portion of the finished element, said movable die device including a tapered die face for engaging and bodily moving the blank during the drawing operation which straightens out said ange.

4. A compound die for producing tapered tubiform elements from sheet stock in one continuous operation, including a stationary die device, a continuously movable die device cooperating with the stationary device during its movement, for drawing a blank of sheet material into tapered form having one end fully open and free of flanges and the other end closed, means included in said devices and operating automatically for piercing the closed end of the blank and leaving a flange, and means embodied in said devices, whereby a continuation of the drawing operation Will straighten out said ilange at one end of a tapered tubiform element fully open and free of anges at both ends, said movable die device including a tapered die face for engaging the tapered portion of the blank and bodily moving the blank throughout the drawingoperation which follows said piercing operation.

5. A compound die for producing tapered tubi- 'form elements from sheet stock in one continuous operation, including a stationary die device, a continuous movable die device cooperating with the stationary device during its movement, for drawing a blank of sheet material into tapered open and the other end is closed, meansc'included in said devices; and operating; automatically for piercing the closed end of the. form sol that a; iange is left, and meansY embodied in said, de-

vices wherebyv a continuationn ofthe drawing4 op'- eration willstraightem out said; flange and; produceV a tapered tubiform element fully openat both ends, said movable die'y device includingV a. 'tapered die face for engaging the taperedfportion of the blank and bodily moving t-he blank throughout the .drawing operation. which follows said piercing operation, said face being roughened to provide av gripping. surface-to'l prevent movement of'the blank rela-tive thereto during said final drawing operation.

6. A compound die for producing tapered tubiform elements from sheet stock in onecontinu'ous operation, including a stationary diedevice, a continuously movable-die device cooperating with the stationary device during its movement, for drawing a blank of-sheet materialV intotapered form free of flanges at one end, means included" in said devices and operating automatically for y'piercing the otherend` of said form so as to produce a flanged open end therefor andA means embodied in said devices wherebya continuation of the drawing operation willv straighten out said yflanged end and produce aA tapered tubiforrn element fully open at both ends, saidmovable` die device including a tapered die face for engaging the tapered portion of the blank and bodily moving the blank throughout the drawing operation 4l which follows said piercing operation, said face i being provided with a series of ribs and grooves anziano f form wherein one end is free. 1f-flanges and fully and; die member having a tapered die face and a punching edge at one endvand adapted to be continuously moved in the space between said blanking and piercing dies while engaged with the blank, said piercing and forming die having a tapered outer face between which and said tapered die face, the blank is drawn into tapered tube free of flanges and fully open at one end and elosedl^ at its other end and a piercing punch operatinginfthefpunch and die member, to pierce the blank; and thereby open said closed end save for an inwardly: extending flange, said blank and said punch and die member moving bodily relative to said piercing, and forming die following saidpiercing operation, to straighten out said flangetand thereby produce a tapered tube free ofy flanges at both ends.

8. A compound die for producing a tapered tubiform element from sheet stock in one continuous operation, including a blanking die, a piercing and forming die located Within and circumferentially spaced from the blanking die, a punch and die member having a tapered die face and a punching edge at one end and adapted to be continuously'moved in the space between said blanking andpiercing dies while engaged with the blank, said piercing and forming die having a tapered outer face, between which and said tapered die face, the blank is continuously drawn into tapered form, and a piercing punch operating in the punch and die member to pierce the blank and thereby render the same tubular with a flange atone end, said blank and said punch and die member moving bodily relative to said piercing and forming diev following said piercing operation, to straighten out said ilange draw the blank into tapered and tubular form free of flanges at both ends, said die face being ribbed to prevent movement' of the blank relative thereto during said final drawing operation.

KENNETH T. NORRIS. 

